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Attic insulation costs, types, and more—a full guide

In this guide, we’ll cover attic insulation cost, attic insulation types (including spray foam attic insulation), and plenty more. Consider this your one-stop shop guide to attic insulation.

In this guide, we’ll cover attic insulation cost, attic insulation types (including spray foam attic insulation), and plenty more. Consider this your one-stop shop guide to attic insulation.

If you’re looking to make your home more comfortable and efficient, insulating your attic is one of the most effective home upgrades you can make. Not only will properly insulating your attic make your home more comfortable right now, but it can also increase your home’s value and decrease your carbon footprint—a good deal all around.

In this guide, we’ll cover attic insulation cost, attic insulation types (including spray foam attic insulation), and plenty more. Consider this your one-stop shop guide to attic insulation, and feel free to skip around to the topics you’re interested in to get your questions answered.

Why you should upgrade your attic insulation

Great question. Here are the two biggest reasons you should upgrade your home’s attic insulation:

1. Attic insulation makes your home more comfortable. 

This is the obvious one. Insulation creates a thermal boundary between your home and the air outside, keeping outside air out and inside air in. When it comes to the attic, creating the best thermal boundary possible is especially important, because your roof where a lot of the inside heat escapes (in the winter) and outside heat comes in (during the summer).

Insulating and air sealing your attic can go a long way toward keeping air where it’s supposed to be (and it’ll make your home a lot more comfortable in the process).

2. Insulating your attic is one of the best ways to boost your home’s efficiency. 

Since so much of the energy you’re buying to heat and cool your house is being lost through the top of your home, insulating your attic can be a great step toward reducing your monthly energy bills. (You might even be able to use the money you save to help pay for the cost of insulation.)

Why do we keep talking about air sealing? See our full guide here.

Does adding attic insulation increase home value?

Yes, insulating your home’s attic (or upgrading existing insulation) can absolutely increase your house value, and—when it comes to your return on your investment—it’s one of the best improvements you can make. Homeowners can recoup an average of 116% of the cost of their attic insulation upgrade, according to a 2016 report from Remodeling magazine. (Compare that to the average financial return on a kitchen upgrade—which is just over 80%.

In short, upgrading your attic insulation is a great investment for long-term home value—plus, it’ll make your life more comfy in the meantime. 

What is R-value? And why is it important to consider when considering attic insulation costs and types?

R-value is a measure of how well a barrier or surface—like a window, wall, or layer of insulation—resists the flow of heat. Here’s one way to think about it: When you pour hot water into a paper cup, it can burn your hand. But if you pour hot water into a thermos, you won’t feel anything. That’s because the thermos has a much higher R-value than paper.

When it comes to insulation, R-value is one of the most important things to consider. The higher the R-value, the more effective the insulation will be at keeping heat inside your house in wintertime or outside your house in summertime—which means your HVAC system won’t have to work as hard throughout the year. (And if your insulation’s R-value is too low for your local climate? A lot of your energy dollars will escape right through the walls and ceiling.)

Why is this important? Lots of houses (especially old houses) are under-insulated; the R-value of the installed insulation isn’t high enough to provide an adequate thermal barrier. And that can make for some chilly winters and muggy summers.

Plenty of homeowners don’t know that their insulation is the problem, though. In fact, many people assume that their home is uncomfortable because their windows are old. And, while windows might be part of the problem, they’re usually not the main issue. 

The fact is that even the priciest, most technologically-advanced windows available will only improve your house’s R-value by a few points. Properly installed insulation, however, can give you a boost in R-value of up to 50 points. (Here’s why you probably don’t need to replace your windows.)  

That’s why we often caution our customers against buying new windows unless absolutely necessary. Yes, new windows can make your home more energy-efficient, but insulation typically makes a far bigger impact on your home’s heating and cooling efficiency.

Insulating the attic: First, how many attics do you have?

Before we jump into attic insulation types and the cost of attic insulation, let’s take a pause and ask a question: How many attics does your home really have?

This question is important because some houses (especially older houses) have multiple kinds of attics. These nooks, crannies, and mini-rooms are easily ignored because they’re usually hard to access or tucked behind hidden doors. In fact, many homeowners don’t even know their home has more than one attic.

The point? These extra attics are often uninsulated or under-insulated, which can play a huge role in your home’s climate control efficiency.

Let’s dive into the types of attics you might find in your home.

Standard upstairs attic

What is a standard upstairs attic?

This is the usual upstairs space we all think of when we think of attics. It’s the place your family probably stored holiday decorations.

Most homes have one of these larger, unfinished spaces, though they’re often used for utility access (think: bathroom fans and electrical wiring) instead of storage needs., but most homes have one of these larger, unfinished spaces.

Why do standard attics matter when it comes to attic insulation?If your main attic isn’t well-insulated and air sealed, you’re going to lose a lot of your energy dollars through the roof. Attics are prime places for heat exchange. In summer, heat will sink into your home through the roof, and in winter, hot air will escape the same way. That’s why your main, upstairs attic should be at the top of your list for an insulation upgrade.

A Cape Cod style house has two knee attics alongside the second floor, and a devil's peak on top.

Knee attics (also called side attics)

What is a knee attic?

Also known as a side attic, these spaces are located at the point where your roofline meets the uppermost portions of your walls. Knee attics are usually found connected to one or more of the bedrooms upstairs, and are especially common in Cape Cod-style homes. If you have one in your house, you might use it as an extra storage space or just ignore it altogether.

Why do knee attics matter when it comes to attic insulation?

Knee attics are often uninsulated and unsealed, which can make your second floor uncomfortably hot in summer and icy cold in winter.

Devil’s peak attic

What is a devil’s peak attic?

A “devil’s peak” is a small attic which partially covers the topmost floor of a house where all or most of the attic has been finished. This type of attic is also very common in a Cape Cod-style house.

Why does a devil’s peak attic matter when it comes to your home’s attic insulation needs?A devil’s peak attic is often inaccessible to the homeowner, so it’s rarely properly air sealed and insulated—which means that there is little to no thermal boundary between the second floor rooms’ ceiling and the roof. In short: it’s a definite culprit when it comes to energy loss in your home. (Because it’s so difficult to access and work in, though, you’ll want to hire the right professional to do the work. This isn’t a good DIY project.)

Flat Roof

What is it?

The anti-attic. A flat roof is a top-floor ceiling with just a small, rectangular cavity above it and below the roof.

Why does a flat roof matter with regards to attic insulation?

Without air sealing and insulation, a flat roof can be a major source of heat loss in winter. In the summer, with the sun beating down on the roof, heat radiates into the rooms below. That said, a flat roof can be tricky to repair. To insulate a flat roof often requires demolition, so we often recommend leaving it alone unless absolutely necessary.

Attic insulation types

Let’s talk about one of the major decisions you’ll need to make when insulating your attic: Which insulation should you use?

Before we go over the various types of insulation, though, an important caveat: Insulating your attic and home can be a complicated task. It’s crucial that you select the right materials and the right spots to insulate, and—most importantly—the right partners to help with the work. While it’s important to educate yourself  about your insulation project, getting professional help is the best way to be sure that the project actually solves your climate control problems.

Okay, let’s dive into the different types of attic insulation available.

Fiberglass attic insulation

When you think about attic insulation, fiberglass insulation is probably what you imagine. It’s often recognizable by its signature pink and yellow colors, and it’s a great choice if you want to insulate areas like knee walls. 

Fiberglass attic insulation often comes in batts, also known as blanket or rolled insulation. But it’s important to note that blanket or batt insulation also comes in other materials, such as cellulose, mineral wool, or even recycled cloth materials. (We’ll specifically be talking through fiberglass here.)

While fiberglass batting is a popular DIY attic insulation solution, it’s not always the best long-term solution for every area of your home. You’ll need to take some extra precautions when using fiberglass, too, because it can be susceptible to moisture and it’s also a favorite snack of raccoons.

Pros of fiberglass insulation:

  • It’s easy on the budget and easy to install.
  • It’s moisture-resistant when a vapor barrier is also used.
  • It requires minimal maintenance.
  • It’s fire-resistant.
  • It has a lower carbon footprint than many other kinds of insulation.

Cons of fiberglass insulation:

  • It can create airborne fibers, which isn’t great for your health or home air quality.
  • It has a lower maximum R-value than some other insulation types.
  • It’s easy to install it incorrectly, which reduces its overall efficiency.
  • It decreases in R-value over time.
  • It’s a favorite snack of raccoons (and we assume you don’t want them in your attic).

Estimated R-value per inch of fiberglass insulation: 2.9 – 4.3

Spray foam attic insulation

One of the newer insulation types, spray foam comes in two varieties: open cell and closed cell. Open cell is lighter, and less dense. It’s better for filling spaces with lots of little nooks and crannies. Closed cell is more dense, completely impermeable, and has a higher R value. But it’s more expensive and can be trickier to install.

Pros of spray foam attic insulation:

  • It offers an air-tight seal (especially when paired with attic air sealing).
  • It doesn’t require a vapor barrier, unlike fiberglass.
  • It’s great in unusual, awkward, and hard-to-insulate spaces.
  • It offers a longer insulation lifespan and doesn’t lose R-value over time.

Cons of spray foam attic insulation:

  • It has a higher upfront cost than other attic insulation types. (However, depending on where you live, you may be able to get spray foam insulation at no upfront cost.)
  • It has a higher carbon footprint than fiberglass insulation.
  • It can shrink in locations with severely fluctuating temperatures.

Estimated R-value per inch: 5 – 6

Cellulose attic insulation

Cellulose is a type of blown insulation made from shredded recycled paper, recycled clothing, and even recycled cardboard boxes (all those Amazon boxes need somewhere to go for their second life). While cellulose doesn’t look pretty, the earth loves it—it has negative lifecycle carbon emissions.

Before installation, the recycled material is treated to make it fire-retardant and pest-repellant. Then it can be blown in to insulate open areas such as attic floors—or packed in more densely to insulate a contained space. (Cellulose insulation comes in batts, too, but blown-in insulation is more common.)

Pros of blown-in cellulose attic insulation:

  • It’s environmentally friendly and usually made of recycled materials.
  • It’s fire-resistant.
  • It’s a budget-friendly option for homeowners.
  • It has lower health risks than fiberglass.

Cons of blown-in cellulose attic insulation:

  • It absorbs moisture easily, which can lead to mold and rot.
  • It can create a lot of dust, especially upon install or removal.
  • Its R-value reduces over time.
  • It requires a vapor barrier.

Estimated R-value per inch: 3.2 – 3.8

Uncommon attic insulation types—alternatives and additions

There are a few alternatives and additions to the standard attic insulation types:

  • Structural insulated panels: These are commonly used when building a new home and aren’t used when upgrading attic insulation.
  • Reflective insulation: This is a layer of foil that may be added to rigid foam, plastic film, or polyethylene bubble insulation to reflect heat.

Attic insulation cost

Attic insulation is one of the home upgrades that can significantly increase your comfort while increasing your house’s long-term value. It’s worth it. The overall cost will depend on the insulation type you use, the size of the attics, and the cost of professional installation and air sealing—and your location matters a lot (the best way to figure out how much attic insulation will cost is to talk to a professional). 

That said, here are some ballpark numbers:

Cost of fiberglass batting insulation

The average cost per square foot for fiberglass insulation is between $0.64 – $1.19, though the exact cost will depend on its thickness, R-value, overall quality, and more.

Cost example: 400 square feet of attic space throughout your home, fiberglass batting insulation materials would cost you between $256 and $476. Keep in mind that this doesn’t include the cost of labor, removing old insulation, or air sealing (which is necessary in most cases).

Here’s why you should air seal your home.

Cost of spray foam attic insulation

The cost of spray foam attic insulation is calculated by what’s called board foot, which is determined not only by square footage, but also depth.

Cost calculations get tricky here, so it’s best to work with a professional for an accurate estimate, but average board foot prices for spray foam attic insulation are below (these costs do not include labor, removing older attic insulation, air sealing):

Cost of blown-in cellulose attic insulation

The average cost for blown-in cellulose attic insulation is between 0.83 and 0.91 for materials.

Again, this doesn’t include labor, air sealing, old insulation removal, or equipment rental to blow in the material. Cost example: For 400 square feet of attic space, the cost of materials alone would ring up at between $332 and $364. Renting a cellulose insulation blower can cost anywhere from $70 to $205 per day (not including a rental deposit).

It’s worth the expense to pay someone who knows what they’re doing. (That’s why Sealed only partners with certified home performance contractors for attic insulation and air sealing.)

Installation costs for insulating your attic

If you’ve done a home improvement project before, you already know that the biggest expense in a project isn’t materials, it’s labor.

The cost to insulate your attic—or anywhere in your home—depends on where you live in the country, and it’s impossible to provide a general estimate. Just know that analyzing your home for energy-efficiency, planning an insulation strategy, and installing the appropriate insulation are difficult tasks that require professional knowhow. It’s worth the expense to pay someone who knows what they’re doing. (That’s why Sealed only partners with certified home performance contractors for attic insulation and air sealing.)

There’s good news: You may not have to pay any of these costs upfront.

Get attic insulation—without breaking the bank.

Depending on where you live, you might be able to get professional attic insulation—with complete attic air sealing—at no upfront cost. You’ll pay us back little by little, and at a rate based on your energy saving. Plus, we’ll guide the project every step of the way—and then stand by our work afterwards. If you don’t save energy, we don’t get paid. It’s as simple as that.

Basically, the Sealed Comfort Plan is a hassle-free and worry-free way to make your home feel amazing.

Want to learn more about how Sealed can help? Give one of our experts a call today at 888-985-7481.

March 1, 2021